For a good background description of the construction and techniques for fabricating semiconductor light-emitting diode lasers, reference is made to the textbook by A. A. Bergh and P. J. Dean entitled "Light-Emitting Diodes"--published by Clarendon Press, Oxford, England 1976 and "Heterostructure Lasers" by H. C. Casey and M. B. Panish--published by Academic Press, 1978.
Semiconductor diode lasers conventionally are modulated by varying the drive current supplied across the p-n junction of the diode laser within which an active layer of photoluminescent light producing semiconductor composition is disposed. Modulation of the emitted laser light beam intensity in this known manner can and does require controlling substantial magnitude drive currents, particularly for high-power rated devices. In addition, there is often a need to design special holding structures for diode lasers to assure that there is proper alignment between the emitted laser light beam spot on the diode laser facet where the emitted laser beam is coupled to a receptor body such as a fiber optic coupling element in an optical communication system, or where the diode is used in an array for display purposes or in a printer. To alleviate some of the stringent physical positioning requirements imposed on such holding structures, it is desirable that some simple, low signal level electrically operable means be provided for physically moving or positioning the emitted light beam spot along the laser facet. It is particularly desirable to provide a semiconductor diode laser in which the above briefly-discussed features and characteristics are embodied in a single device.
Low power signal level, gate controlled, fast modulation of the emitted light beam intensity of a semiconductor diode laser has been disclosed in a number of prior art U.S. patents, included amongst which are the following: U.S. Pat. No. 4,430,741 issued February 7, 1984 for a "Semiconductor Laser Device"--Tadashi Fukuzawa, Michiharu Nakamura and Susumu Takahashi, inventors; U.S. Pat. No. 4,700,353 issued October 13, 1987 for "Active Modulation of Quantum Well Lasers by Energy Shifts in Gain Spectra with Applied Electric Field"--Edward Van Gieson, Gary W. Wicks, Eric Elias and Lester F. Eastman, inventors; U.S. Pat. No. 4,534,033 issued August 6, 1985 for a "Three Terminal Semiconductor Laser"--Jun-ichi Nishizawa, Tadahiro Ohmi, Masakazu Morishita, inventors; U.S. Pat. No. 3,959,808 issued May 25, 1976 for a "Variable Stripe Width Semiconductor Laser"--Frederick David King, inventor; and U.S. Pat. No. 4,152,711 issued May 1, 1979 for a "Semiconductor Controlled Luminescent Device"--Josuke Nakata, inventor.
Electrically controlled scanning of the position and direction of the emitted laser light beam from semiconductor diode lasers is disclosed in U.S. Pat. No. 4,296,386 issued October 20, 1981 for a "Semiconductor Injection Laser Having a Movable Laser Beam"--Rudolf P. Tijourg, Peter J. de Waard and Teunis van Dongen, inventors, and U.S. Pat. No. 4,475,200 issued October 2, 1984 for a "Semiconductor Laser Beam Scanner"--Chien-Ping Lee, inventor.
None of the above-listed prior art U.S. patents disclose or make available to the industry a single semiconductor diode laser device which is capable both of low signal level, electrical controlled modulation of the emitted laser light beam intensity including turn-on and turn-off of the beam, and physical movement to provide scanning of the position of the emitted laser light beam spot along the facet of the laser.